#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define USER "USER"  

int main()
{
  char* who = getenv(USER); 
  if ((strcmp(who, "root")) == 0)
  {
    printf("user: %s\n", who);
  }
  else 
  {
    printf("权限不足!\n");
  }
  return 0;
}
